1. Field of the Invention
The present invention relates to a reflective liquid-crystal display apparatus and a manufacturing method thereof.
2. Description of the Related Art
In a reflective liquid-crystal display apparatus, incident light is transmitted through a transparent substrate, an opposite electrode, and a liquid crystal layer, and is reflected by a reflective electrode. When a voltage is applied between the reflective electrode and the opposite electrode, the alignment state of liquid crystal molecules within the liquid crystal layer changes, and thus the intensity of the reflected light changes. Silicon oxide is typically used in an insulating layer of the reflective liquid-crystal display apparatus. Because silicon oxide has high light transmittance, a portion of the incident light enters from a reflective electrode gap between pixels, and intrudes into a semiconductor substrate below the reflective electrode. As a result, an electron-hole pair is produced by photoelectric conversion in the semiconductor substrate. When this electron or hole reaches an accumulation capacitor for holding the voltage of each reflective electrode, an unintended voltage change of pixel electrodes is invited, thus degrading the quality of a displayed image.
In Japanese Patent Laid-Open No. 2004-198764, a metal film formed on a metal layer is patterned to form a metal protruding portion, and thereon an insulating layer and then a metal layer are formed in order. Thus, incident light that has intruded into the insulating layer can be scattered by the protruding portion, thereby suppressing the intrusion of incident light into the semiconductor substrate. However, in recent liquid crystal display apparatuses, there have been advances regarding increased resolution and brightness, and the size of a single pixel has been reduced. As a result, the reflective electrode gap between pixels and the wavelength of light used for display (400 nm to 800 nm) have become about the same, and a portion of incident light that passes through a narrow slit between reflective electrodes between pixels is diffracted and proceeds in a direction approximately parallel (the lateral direction) to the substrate face. Incident light that has been diffracted in this way unintentionally arrives at the semiconductor substrate without being scattered by the metal protruding portion. Therefore, the insulating layer between the metal protruding portion and the metal layer over the metal protruding portion is desired to be as thin as possible.
In the technology described in Japanese Patent Laid-Open No. 2004-198764, incident light is merely scattered by forming the protruding portion in the metal layer, and there is no investigation of reducing incident light that passes through by adopting a small thickness of insulating layer on the protruding portion. As a result, it is not possible to adequately reduce the amount of incident light arriving at a circuit element. In liquid crystal display apparatuses, technology regarding increased resolution and brightness is advancing. Accordingly, the amount of light that is incident per unit area of such liquid crystal display apparatuses is increasing.